Add Deck workflow automation Nextcloud app

Ports the standalone due-date cron script into a proper Nextcloud 34
app with a personal-settings UI, per-user workflow configuration
(source/target stack, assigned-user and label filters, email
notification), a TimedJob background runner, and Gitea CI pipelines.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitea/workflows/build-release.yml

@@ -0,0 +1,35 @@
+name: Build release artifact
+
+on:
+  push:
+    tags:
+      - 'v*'
+
+jobs:
+  package:
+    runs-on: gitea-runner-server03
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: '24'
+
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.3'
+          coverage: none
+
+      - name: Install JS dependencies
+        run: npm ci
+
+      - name: Build frontend
+        run: npm run build
+
+      - name: Package appstore artifact
+        run: make appstore
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: workflow_deck_automation-${{ gitea.ref_name }}
+          path: build/artifacts/appstore/*.tar.gz

.gitea/workflows/lint-info-xml.yml

@@ -0,0 +1,23 @@
+name: Lint info.xml
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  xml-lint:
+    runs-on: gitea-runner-server03
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install xmllint
+        run: |
+          apt-get update
+          apt-get install -y --no-install-recommends libxml2-utils
+
+      - name: Download appstore schema
+        run: wget -q https://raw.githubusercontent.com/nextcloud/appstore/master/nextcloudappstore/api/v1/release/info.xsd -O info.xsd
+
+      - name: Validate appinfo/info.xml
+        run: xmllint --schema info.xsd appinfo/info.xml --noout

.gitea/workflows/lint-php.yml

@@ -0,0 +1,24 @@
+name: Lint PHP
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  php-lint:
+    runs-on: gitea-runner-server03
+    strategy:
+      matrix:
+        php-version: ['8.2', '8.3', '8.4']
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-version }}
+          coverage: none
+
+      - name: Syntax check
+        run: |
+          find lib tests appinfo -name '*.php' -print0 | xargs -0 -n1 -- php -l

.gitea/workflows/phpunit.yml

@@ -0,0 +1,24 @@
+name: PHPUnit
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  unit-tests:
+    runs-on: gitea-runner-server03
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.3'
+          extensions: sqlite, pdo_sqlite
+          coverage: none
+
+      - name: Install dependencies
+        run: composer install --no-progress --prefer-dist
+
+      - name: Run unit tests
+        run: composer run test:unit